The next aspect of field fortifications to consider are the interior arrangements. Thus far most of our focus has been towards the exterior, with the exception of the traverses, and what could be done to block or stop the attacker. With the interior arrangements, the engineer would consider what could make the defenders’ job easier and, shall we say, more comfortable. Mahan prefaced his lesson on interior arrangements by calling attention to such factors:

Under the [heading] of interior arrangements is comprised all the means resorted to within the work to procure an efficient defense; to preserve the troops and the material from the destructive effects of the enemy’s fire; and to prevent a surprise.

You are probably thinking, “protect the troops? Isn’t that what the parapet does? Doesn’t the ditch prevent surprise?” Well… yes… you might look at it from that standpoint. But what Mahan was calling attention to here were the structures and features which were internal to the works and designed to improve the nature of the defense. As such “within the work” is the important phrase to consider. But, keep your questions in mind as we work through this topic, as we will revisit shortly.

Mahan continued to offer a list of classes of these interior arrangements:

The class of constructions required for the above purposes, are batteries; powder magazines; traverses; shelters; enclosures for gorges and outlets; interior safety-redoubt, or keep; and bridges of communication.

From that we have a subdivision:

All arrangements made for the defense, with musketry and artillery, belong to what is termed the armament.

So we have a name for structures to support things that shoot. Armaments. Just for the context of these field fortification discussions, OK?

The armament with musketry is complete when the banquette and the interior and superior slopes are properly arranged, to enable the soldier to deliver his fire with effect; and to mount on the parapet to meet the enemy with the bayonet. For this last purpose stout pickets may be driven into the interior slope, about midway from the bottom and three feet apart. The armament with artillery is, in a like manner, complete, when suitable means are taken to allow the guns to fire over the parapet, or through openings made in it; and when all the required accessories are provided for the service of the guns.

So… yes the parapet’s design can be considered part of the interior arrangements.

Mahan continues with this profound statement:

The armament with artillery is a subject of great importance….

You got me at “great importance.”

Oh, wait, I cut the professor off. He has more on this ….

The armament with artillery is a subject of great importance, because it is not equally adapted to all classes of works. Experience has demonstrated that the most efficient way of employing artillery, is in protecting the collateral salients by a well directed flank and cross fire, which shall not leave untouched a single foot of ground within its range, over which the enemy must approach. It has moreover shown, that a work with a weak profile affords but little security to artillery within it; for artillery cannot defend itself, and such a work can be too easily carried by assault to offer any hope of keeping the enemy at a distance long enough to allow the artillery to produce its full effect.

The logic here is “form should follow function.” If the intent is to have artillery fire on the enemy in order to break up the attack, then a flank fire is recommended. And that artillery should blanket the approaches with fire… “shall not leave untouched a single foot….” Artillery sits at the top of the list when making decisions about weapon placement. It is the most effective, man per man, weapon for influencing the battlefield Not necessarily saying “killing” or producing causalities, but influencing the other side’s actions. Yet, artillery’s influence is best gained over longer ranges. Thus the need to form works that not only provide the artillery a measure of protection but also keep the enemy at greater than small arms length (range).

The best position for artillery is on the flanks and salients of a work; because from these points the salients are best protected, and the approaches best swept; and the guns should be collected at these points in batteries of several pieces; for experience has likewise shown, that it is only by opening a heavy, well-sustained fire on the enemy’s columns, that an efficient check can be [given] to them. If only a few files are taken off, or the shot passes over the men, it rather inspires the enemy with confidence in his safety, and with contempt for the defenses.

Sun Tzu should have said it! Don’t let the enemy become contemptuous of your defenses!

Consider the “best practice” offered by Mahan. By placing artillery on the salients, the guns were out of the direct line of the attacker’s fires while being placed behind the various, and likely complex, defensive works on the “horns” of the bastion. And artillery shouldn’t be parceled out as singles, but rather massed and inter-operated to multiply the effect.

All this is great theoretical talk. Everyone would agree massing artillery is best. But now we have a practical problem on the parapet. With infantry, the parapet works fine to protect most of the body, provide cover to crouch behind when reloading, and, if the fight is close, an orientation for the bayonets. But artillerymen cannot “crouch” an artillery piece. And when servicing the weapon, they are exposed. Furthermore, there are all sorts of problems bringing 12 pound or 24 pound or larger projectiles up to the gun. So to make the big guns work best, one must make arrangements.. in the interior…. And those arrangements Mahan identified under the classification of “batteries.” We’ll look at those next.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 51-2.)

One thought on “Fortification Friday: Interior Arrangements, starting with armaments”

Graig: I enjoy your Fortification Friday series. I always work Mahan’s words back to our friends the Washington Artillery and their field fortifications on Marye’s Heights during the battle of Fredericksburg. These were laid out and constructed as Barbette by the engineers and modified as embrasure with traverses by the artillerymen in time for the battle. Because none of these survived post-war it is of interest to understand what the “book” or school solution might have been, and what might have been done to field adapt Mahan’s model. Keep up the good work!